1. Bedding or Stratification

Source: Steven, E. (2015)

• Definition:
  • The arrangement of sedimentary rocks in distinct horizontal layers.
  • Formed by continuous sediment deposition over time.
• Significance:
  • Indicates variations in environmental conditions.
  • Helps reconstruct past depositional environments.

2. Graded Bedding

Source: https://epod.usra.edu

• Definition:
  • A type of layering where particle size gradually decreases from bottom to top.
• Formation:
  • Occurs due to rapid sediment deposition from turbidity currents in deep marine settings.
• Significance:
  • Helps determine paleocurrent direction.
  • Used in identifying underwater landslides and ancient marine conditions.

3. Cross Bedding

Source: Steven, E. (2015)

Source: Steven, E. (2015)

• Definition:
  • Inclined layers within horizontal beds.
  • Forms when sediment is deposited by wind or water currents at an angle.
• Formation:
  • Common in sand dunes, river channels, and shallow marine environments.
• Significance:
  • Indicates paleocurrent direction.
  • Used to reconstruct ancient wind or water flow conditions.

4. Ripple Marks

Source: https://blogs.egu.eu

• Definition:
  • Small ridges formed on sediment surfaces due to water or wind action.
• Types:
  • Symmetrical Ripples → Formed by wave action (bidirectional movement).
    
  • Asymmetrical Ripples → Formed by unidirectional currents (e.g., river flow).
• Significance:
  • Provides insights into paleocurrent direction and energy conditions of deposition.

5. Mud Cracks

Source: Steven, E. (2015)

• Definition:
  • Polygonal cracks formed when wet mud dries and contracts.
• Formation:
  • Common in floodplains, tidal flats, and lake beds.
• Significance:
  • Indicates periods of drying and subaerial exposure.
  • Helps interpret ancient climate conditions.

1. Stream Sediments

Depositional Features:

• Bars → Mid-channel sediment accumulations.
• Point Bar → Forms inside a meander curve due to slower water velocity.
• Meander Loop → Large bends in river channels, leading to sediment deposition.

Significance:

• Reflects river energy and erosion-deposition balance.
  
• Helps in paleogeographic reconstructions.

2. Braided Stream Deposits

Source: https://www.coolgeography.co.uk

• Definition:
  • A river system with multiple interwoven channels separated by sediment bars.
• Formation:
  • Occurs in high-energy environments with fluctuating discharge (e.g., glacial meltwater rivers).
• Sediment Characteristics:
  • Poorly sorted, coarse sediments (gravel and sand).
• Significance:
  • Common in arid regions, glacial outwash plains, and mountain valleys.

3. Floodplain Sediments

Source: https://www.coolgeography.co.uk

Depositional Features:

• Floodplain → Flat, low-lying area adjacent to a river, covered by water during floods.
• Natural Levee → Elevated ridges of sediment deposited along riverbanks during flooding.

Significance:

• Indicates periodic flooding events.
• Supports agricultural development due to nutrient-rich soils.

4. Delta and Alluvial Fan Sediments

Source: https://abhipedia.abhimanu.com

Delta Deposits

• Definition:
  • A sediment accumulation where a river meets a standing body of water (lake or ocean).
• Sediment Characteristics:
  • Finer sediments due to energy reduction (sand, silt, and clay).
• Examples:
  • Nile Delta, Mississippi Delta.

Alluvial Fan Deposits

• Definition:
  • Fan-shaped sedimentary deposits at the base of mountain slopes.
• Formation:
  • Caused by sudden loss of river velocity as it exits a mountain valley.
• Sediment Characteristics:
  • Coarse, poorly sorted sediments (gravel and sand).

Significance:

• Indicates tectonic uplift and climatic changes.
• Associated with flash flood environments.

Delta vs Alluvial Fan

Summary

• Sedimentary Structures:
  • Bedding, graded bedding, cross-bedding, ripple marks, and mud cracks.
• Waterway Depositional Features:
  • Stream sediments, braided streams, floodplains, deltas, and alluvial fans.
• Significance:
  • Helps reconstruct paleoenvironmental conditions and sedimentary processes.